GARFIELD HEIGHTS, Ohio – A Garfield Heights man accused of killing his girlfriend’s two teenage children during a domestic incident made his first court appearance on Friday morning.

Matthew Nicholson, 29, is charged with two counts of murder and three counts of domestic violence in the fatal shootings that led to a SWAT standoff late Wednesday at a home on East 86th Street near Garfield Boulevard.

Nicholson argued with his girlfriend before he shot her children Giselle Lopez, 19, and Manuel Lopez Jr., 17, police said. The fight began after Nicholson became angry over text messages his girlfriend received from an ex-boyfriend, police said.

Nicholson waived his right to a preliminary hearing during his initial appearance Friday in Garfield Heights Municipal Court. The case was bound over to a Cuyahoga County grand jury.

Judge Deborah J. Nicastro set his bond at $500,000. Nicastro also imposed a temporary protection order that prohibits Nicholson from contacting the girlfriend.

Several of Nicholson’s relatives were in the courtroom Friday, but they declined to comment after the hearing. Nicholson’s attorney, Michael Goldberg, also declined to comment.

Neighbors told cleveland.com that Nicholson regularly fought with his girlfriend, but Garfield Heights police said he did not have a prior record of domestic violence.

Nicholson became angry on Wednesday evening about the texts his girlfriend received from her ex-boyfriend. The argument turned physical, and Manuel Lopez Jr. tried to defend his mother. Giselle Lopez arrived home from work at roughly the same time and also intervened, according to police reports.

Nicholson threatened to kill everyone before the mother and her two children walked out the front door. He then grabbed a handgun and fired at them, hitting both children, police reports say.

The mother then ran to a neighbor’s home and asked her to call 911, saying “he shot my babies,” the neighbor told cleveland.com.

Garfield Heights police officers arrived just after 9:30 p.m. and found both teens shot in the driveway outside the home. Manuel Lopez Jr. was pronounced dead after being taken to Marymount Hospital. Giselle Lopez was taken to MetroHealth, where she died during surgery.

A SWAT team was called to the home because Nicholson barricaded himself inside. He was wearing body armor when he surrendered about 1:40 a.m., police said.

Garfield Heights police Chief Robert Byrne said Thursday that Nicholson worked as a private security officer contracted by the United States Department of Homeland Security. He was employed by Paragon Systems, a Virginia-based company contracted to provide security for federal buildings, police said.

Giselle Lopez graduated from Garfield Heights High School last year with a 4.13 GPA, and was studying at Cuyahoga Community College to become a nurse. Manuel Lopez Jr. also attended Garfield Heights High School.

The teens’ father, Manuel Lopez, told cleveland.com on Thursday that he remained close with them after he divorced their mother in 2011. He described them as good, hard-working kids.

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